Montague
Clear Sky Chart
History

This sumarizes the distribution of each different forecast outcome for the Montague clear sky chart from 2005-11-06 to 2024-02-05.

This page is a summary of past forecasts. Even though it's based only on forecasts, some people use these pages as clue to a site's climate. But climate data based on actual observation should be preferred (if you can find it!).

Cloud, Transparency and Seeing forecasts are summarized individually. But because good observing conditions require a combination of minimum cloud cover, transparency and seeing, the individual forecast summaries can be difficult to interpret. The observing conditions section counts the combinations of conditions needed for common types of astronomical observation.

Observing Conditions

The following tables count the occurrence of the combinations of forecast and darkness conditions needed for different observations. Conditions are rated by by what percentage of the hours the observation would likely be attempted are usable.
Observation TypeMinimum conditions for hour to be usableOut of hours
Clear of CloudsTransparencySeeingSky Brightness
Planetary:50%(no limit)Average(no limit)Nighttime Hours
Deep Sky:70%Average(no limit)5.9Nighttime Hours
CCD Imaging:70%Below AveragePoor(no limit)Nighttime Hours

Percentages are of nighttime hours per month, or per year, when a particular observing conditions was met. Deep Sky percentages never exceed 50% because the moon is up half the time. Deep sky percentages are much lower for charts at high latitudes because of fewer dark hours in the summer.

Overall

PlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
Night
30%
23138
19%
80161
9%
23048
42%
23048
19%
51010

By Month

MonthDays of MonthPlanetaryData
Pts
Deep Sky
Max 60%
Data
Pts
Both Planetary and Deep Sky
Max 60%
Data
Pts
Either Planetary or Deep SkyData
Pts
CCD ImagingData
Pts
January1st to 10thNight
16%
753
22%
4342
6%
737
36%
737
10%
2482
January11th to 20thNight
20%
760
20%
4348
7%
740
34%
740
8%
2740
January21st to endNight
16%
832
14%
4547
5%
814
36%
814
9%
3041
February1st to 10thNight
17%
739
17%
2399
5%
739
33%
739
16%
1566
February11th to 20thNight
12%
703
20%
2144
4%
700
33%
700
15%
1410
February21st to endNight
15%
592
24%
1776
8%
592
35%
592
14%
1191
March1st to 10thNight
17%
720
21%
2160
7%
720
35%
720
19%
1364
March11th to 20thNight
20%
720
21%
2016
7%
720
34%
720
20%
1312
March21st to endNight
18%
792
22%
2030
6%
792
31%
792
21%
1371
April1st to 10thNight
21%
720
18%
1800
4%
720
29%
720
19%
1278
April11th to 20thNight
23%
711
18%
1775
4%
711
30%
711
23%
1232
April21st to endNight
26%
720
19%
1800
5%
720
34%
720
24%
1249
May1st to 10thNight
26%
508
16%
1588
9%
508
32%
508
16%
1107
May11th to 20thNight
28%
354
21%
1416
12%
354
43%
354
18%
862
May21st to endNight
45%
388
16%
1551
15%
388
53%
388
21%
920
June1st to 10thNight
46%
360
18%
1440
18%
360
56%
360
21%
859
June11th to 20thNight
42%
360
16%
1440
13%
360
54%
360
22%
858
June21st to endNight
51%
360
16%
1440
15%
360
61%
360
29%
788
July1st to 10thNight
55%
350
15%
1400
18%
350
60%
350
24%
813
July11th to 20thNight
55%
348
17%
1392
20%
348
59%
348
24%
803
July21st to endNight
55%
394
18%
1486
18%
372
62%
372
26%
826
August1st to 10thNight
55%
485
18%
1549
14%
483
60%
483
31%
930
August11th to 20thNight
54%
680
15%
1744
9%
680
56%
680
29%
1204
August21st to endNight
51%
792
19%
1980
8%
792
54%
792
32%
1307
September1st to 10thNight
45%
720
21%
1800
8%
720
51%
720
32%
1178
September11th to 20thNight
46%
720
28%
1844
16%
720
53%
720
35%
1134
September21st to endNight
44%
720
27%
1980
18%
720
52%
720
31%
1258
October1st to 10thNight
38%
720
18%
2131
13%
720
45%
720
23%
1406
October11th to 20thNight
34%
720
22%
2160
12%
720
48%
720
26%
1337
October21st to endNight
26%
792
20%
2488
11%
792
39%
792
22%
1600
November1st to 10thNight
33%
740
24%
2407
12%
740
49%
740
25%
1404
November11th to 20thNight
27%
760
25%
2470
11%
760
45%
760
21%
1531
November21st to endNight
27%
760
22%
2617
10%
760
44%
760
21%
1569
December1st to 10thNight
22%
760
18%
2660
7%
760
36%
760
14%
1750
December11th to 20thNight
21%
760
16%
3220
5%
759
35%
759
12%
2090
December21st to endNight
19%
825
12%
4821
6%
817
36%
817
9%
3240

Individual Forecasts

The length of each colored bar in the "occurrence of each Forecast" column is proportional to the number of times the chart forecast that color. The percentages are of the total number of hours per month, or per year, with a particular forecast. The colors as the same as those used in clear sky charts.

Note: Transparency probabilities are only counted for those hours that have 30% or less cloud cover. Seeing probabilities are only counted for those hours that have 80% or less cloud cover. If that's too tricky, try Observing Conditions instead.

Overall

Occurrence of each ForecastData
Points
Cloud CoverDay
16%7%36%5%35%5%5%7%37%
78165
Night
17%7%35%5%3445%7%40%
80688
TransparencyDay
47%311%23%14%2
77870
Night
45%311%24%15%2
80517
SeeingDay
25%15%28%19%9%3
13825
Night
23%14%28%26%9%1
23161

By Month

Percentage Cloud Cover NE (2006-)
Color Meanings:
Overcast 90% covered 80% covered 70% covered 60% covered 50% covered 40% covered 30% covered 20% covered 10% covered Clear
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
14%9%35%5%3445%5%43%
2517
11th to 20thDay
14%11%5%8%7%44445%32%
2520
21st to endDay
21%11%46%6%25%45%5%31%
3060
February1st to 10thDay
17%7%5%7%6%45%5%5%6%33%
1656
11th to 20thDay
14%8%36%6%4445%7%39%
1703
21st to endDay
19%10%35%5%34447%34%
1480
March1st to 10thDay
13%7%36%7%4445%7%40%
1797
11th to 20thDay
15%7%46%6%46%45%8%36%
1941
21st to endDay
20%8%35%5%34446%37%
2326
April1st to 10thDay
17%8%35%6%4445%6%38%
2160
11th to 20thDay
18%6%35%5%44447%40%
2134
21st to endDay
19%6%26%5%45%5%6%6%37%
2160
May1st to 10thDay
23%7%26%5%3445%6%34%
2385
11th to 20thDay
20%5%25%5%36%5%6%7%36%
2478
21st to endDay
15%5%35%6%45%5%6%8%39%
2725
June1st to 10thDay
16%5%35%6%46%5%5%9%36%
2520
11th to 20thDay
17%5%36%5%36%6%6%9%33%
2520
21st to endDay
13%5%27%7%35%5%5%9%38%
2520
July1st to 10thDay
12%6%26%6%5%5%6%6%9%37%
2520
11th to 20thDay
11%5%35%5%46%6%8%9%39%
2520
21st to endDay
12%6%35%6%45%6%6%9%38%
2744
August1st to 10thDay
11%6%36%6%46%7%8%9%35%
2376
11th to 20thDay
12%6%27%6%47%7%6%8%36%
2138
21st to endDay
15%6%25%435%46%8%42%
2376
September1st to 10thDay
16%6%25%5%3446%7%41%
2160
11th to 20thDay
14%5%2343445%7%49%
2116
21st to endDay
16%6%35%5%35%5%5%7%40%
1980
October1st to 10thDay
22%6%25%5%3345%7%39%
1827
11th to 20thDay
16%6%35%5%345%5%8%40%
1800
21st to endDay
23%6%25%5%35%5%5%6%35%
1866
November1st to 10thDay
14%7%25%423346%50%
1671
11th to 20thDay
19%7%2342446%6%43%
1710
21st to endDay
17%7%346%25%6%5%7%38%
1561
December1st to 10thDay
18%10%36%6%35%45%7%33%
1520
11th to 20thDay
21%7%36%43436%6%36%
1906
21st to endDay
19%12%5%9%7%35%5%46%25%
2772
January1st to 10thNight
16%7%35%5%3446%7%40%
4429
11th to 20thNight
14%9%48%6%35%45%6%36%
4440
21st to endNight
23%11%35%5%3445%5%32%
4593
February1st to 10thNight
17%8%35%5%35%45%7%39%
2399
11th to 20thNight
16%6%36%5%45%5%5%7%38%
2142
21st to endNight
18%7%37%5%35%35%6%38%
1776
March1st to 10thNight
15%7%36%42445%7%44%
2150
11th to 20thNight
17%7%25%43445%7%42%
2015
21st to endNight
16%7%36%4345%6%7%39%
2030
April1st to 10thNight
17%7%47%5%35%45%7%36%
1800
11th to 20thNight
18%6%35%5%45%5%47%39%
1775
21st to endNight
20%6%35%5%25%46%6%39%
1800
May1st to 10thNight
22%8%45%5%35%446%34%
1588
11th to 20thNight
18%6%35%5%3446%7%40%
1415
21st to endNight
14%5%25%5%345%5%8%42%
1550
June1st to 10thNight
17%5%246%34448%43%
1440
11th to 20thNight
14%6%345%35%5%6%8%42%
1440
21st to endNight
12%425%4245%6%9%47%
1440
July1st to 10thNight
12%5%35%5%4447%9%43%
1440
11th to 20thNight
12%5%25%436%5%7%9%43%
1440
21st to endNight
12%4245%35%6%7%9%44%
1574
August1st to 10thNight
10%5%36%5%35%6%6%9%44%
1559
11th to 20thNight
12%6%25%6%46%5%6%8%38%
1744
21st to endNight
15%425%5%45%5%5%8%43%
1980
September1st to 10thNight
16%5%245%3445%7%45%
1800
11th to 20thNight
14%5%24423346%52%
1844
21st to endNight
16%5%345%34447%45%
1980
October1st to 10thNight
22%6%24423446%42%
2131
11th to 20thNight
18%5%24423446%46%
2160
21st to endNight
23%7%2442345%6%41%
2488
November1st to 10thNight
13%6%2443435%6%49%
2407
11th to 20thNight
19%6%3442435%6%44%
2470
21st to endNight
14%6%26%5%345%5%7%44%
2617
December1st to 10thNight
19%7%35%5%45%5%6%7%35%
2660
11th to 20thNight
19%8%35%5%36%5%5%6%36%
3288
21st to endNight
21%10%46%6%3445%6%31%
4884

Transparency (when cloud cover <= 30%)
Color Meanings:
Too cloudy to forecast Poor Below Average Average Above average Transparent
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
46%29%32%8%3
2518
11th to 20thDay
56%210%20%10%2
2520
21st to endDay
55%210%21%10%1
3060
February1st to 10thDay
52%312%19%13%1
1656
11th to 20thDay
47%38%22%16%2
1712
21st to endDay
51%38%23%13%3
1480
March1st to 10thDay
45%212%24%14%3
1800
11th to 20thDay
48%410%23%14%2
1941
21st to endDay
50%37%18%18%5%
2326
April1st to 10thDay
47%39%21%15%4
2160
11th to 20thDay
46%310%22%17%3
2134
21st to endDay
48%38%22%14%4
2160
May1st to 10thDay
51%38%20%14%3
2385
11th to 20thDay
48%49%21%15%2
2482
21st to endDay
43%5%15%22%13%2
2725
June1st to 10thDay
46%5%12%22%14%1
2520
11th to 20thDay
46%5%12%24%11%2
2520
21st to endDay
43%412%27%13%
2520
July1st to 10thDay
44%412%22%16%2
2450
11th to 20thDay
38%415%26%14%1
2445
21st to endDay
43%5%11%22%16%3
2591
August1st to 10thDay
44%5%13%25%14%
2362
11th to 20thDay
45%5%12%25%12%1
2138
21st to endDay
41%410%24%18%3
2376
September1st to 10thDay
42%5%11%23%17%2
2160
11th to 20thDay
37%29%24%25%3
2116
21st to endDay
44%49%21%21%2
1980
October1st to 10thDay
46%410%22%16%2
1827
11th to 20thDay
42%311%26%17%1
1800
21st to endDay
50%310%21%15%2
1866
November1st to 10thDay
38%312%26%19%3
1671
11th to 20thDay
42%210%25%18%3
1710
21st to endDay
44%5%13%27%10%2
1561
December1st to 10thDay
52%315%17%12%2
1520
11th to 20thDay
49%315%22%9%1
1906
21st to endDay
62%39%18%8%
2772
January1st to 10thNight
45%210%30%10%3
4429
11th to 20thNight
52%210%23%11%2
4440
21st to endNight
55%29%23%10%1
4593
February1st to 10thNight
46%314%23%12%1
2399
11th to 20thNight
46%410%21%16%4
2144
21st to endNight
48%26%25%16%3
1776
March1st to 10thNight
42%212%26%14%3
2160
11th to 20thNight
43%311%24%16%2
2016
21st to endNight
44%39%20%19%4
2030
April1st to 10thNight
49%310%21%15%3
1800
11th to 20thNight
46%310%21%20%1
1775
21st to endNight
45%48%23%16%4
1800
May1st to 10thNight
52%39%19%15%2
1588
11th to 20thNight
44%312%20%18%2
1416
21st to endNight
40%6%16%23%13%2
1551
June1st to 10thNight
42%411%25%18%1
1440
11th to 20thNight
41%415%28%11%1
1440
21st to endNight
34%416%30%14%1
1440
July1st to 10thNight
39%5%15%25%15%3
1400
11th to 20thNight
37%7%14%29%12%1
1392
21st to endNight
34%6%18%22%18%2
1486
August1st to 10thNight
37%5%15%27%15%1
1549
11th to 20thNight
43%5%15%23%13%1
1744
21st to endNight
40%412%22%21%2
1980
September1st to 10thNight
39%412%27%17%1
1800
11th to 20thNight
35%310%24%26%2
1844
21st to endNight
40%38%25%23%1
1980
October1st to 10thNight
45%310%24%16%2
2131
11th to 20thNight
40%312%30%14%1
2160
21st to endNight
44%312%25%15%1
2488
November1st to 10thNight
37%312%24%21%3
2407
11th to 20thNight
43%210%23%19%3
2470
21st to endNight
41%214%30%12%1
2617
December1st to 10thNight
49%312%24%12%1
2660
11th to 20thNight
50%312%19%14%2
3288
21st to endNight
56%211%22%8%
4884

Seeing (when cloud cover <= 80%)
Color Meanings:
Too cloudy to forecast Bad 1/5 Poor 2/5 Average 3/5 Good 4/5 Excellent 5/5
MonthDays in MonthOccurrence of each ForecastData
Points
January1st to 10thDay
36%22%24%14%4
180
11th to 20thDay
42%22%28%7%2
180
21st to endDay
30%27%31%7%32
279
February1st to 10thDay
36%26%28%8%2
252
11th to 20thDay
37%24%29%9%1
371
21st to endDay
36%24%25%12%2
346
March1st to 10thDay
30%22%30%15%3
420
11th to 20thDay
30%24%29%12%41
420
21st to endDay
32%22%30%10%5%2
462
April1st to 10thDay
32%21%27%14%5%1
420
11th to 20thDay
28%22%26%14%8%2
412
21st to endDay
31%18%31%13%5%2
420
May1st to 10thDay
36%17%25%13%7%2
423
11th to 20thDay
23%19%30%17%8%2
447
21st to endDay
21%9%28%25%14%3
485
June1st to 10thDay
20%13%31%21%12%3
450
11th to 20thDay
22%12%26%26%12%2
450
21st to endDay
17%11%33%26%12%2
450
July1st to 10thDay
18%6%29%24%17%7%
445
11th to 20thDay
13%6%25%33%20%4
444
21st to endDay
15%7%36%27%12%4
488
August1st to 10thDay
13%6%28%31%15%7%
446
11th to 20thDay
15%6%23%32%18%6%
439
21st to endDay
15%10%29%23%15%8%
495
September1st to 10thDay
24%9%24%23%13%7%
450
11th to 20thDay
16%10%29%20%14%11%
450
21st to endDay
23%9%30%21%12%6%
450
October1st to 10thDay
29%9%22%20%14%5%
450
11th to 20thDay
21%17%29%22%10%2
450
21st to endDay
31%14%30%17%7%1
437
November1st to 10thDay
22%19%24%23%11%2
365
11th to 20thDay
29%18%26%20%6%1
370
21st to endDay
32%19%29%15%41
221
December1st to 10thDay
36%19%29%10%5%
180
11th to 20thDay
40%19%29%9%3
180
21st to endDay
31%18%35%12%41
198
January1st to 10thNight
25%21%33%18%3
760
11th to 20thNight
28%19%28%22%3
760
21st to endNight
23%22%33%20%3
836
February1st to 10thNight
26%19%32%21%1
739
11th to 20thNight
27%23%34%15%1
703
21st to endNight
32%20%28%18%2
592
March1st to 10thNight
28%19%32%18%3
720
11th to 20thNight
27%20%29%19%4
720
21st to endNight
25%20%33%16%6%
792
April1st to 10thNight
25%19%31%20%5%
720
11th to 20thNight
23%17%32%20%7%
711
21st to endNight
27%13%30%24%6%
720
May1st to 10thNight
27%11%30%25%7%1
508
11th to 20thNight
23%11%32%28%7%1
354
21st to endNight
17%6%23%40%13%1
389
June1st to 10thNight
19%6%20%37%16%1
360
11th to 20thNight
17%5%29%36%13%
360
21st to endNight
13%425%44%14%1
360
July1st to 10thNight
13%5%20%41%20%1
350
11th to 20thNight
14%222%44%18%1
348
21st to endNight
12%6%20%43%17%2
394
August1st to 10thNight
10%321%40%24%2
485
11th to 20thNight
15%316%39%24%2
680
21st to endNight
16%5%20%35%22%2
792
September1st to 10thNight
18%6%23%33%17%3
720
11th to 20thNight
17%6%24%28%20%5%
720
21st to endNight
20%6%24%30%18%3
720
October1st to 10thNight
26%10%20%27%16%2
720
11th to 20thNight
22%11%27%31%9%
720
21st to endNight
28%14%28%22%8%
792
November1st to 10thNight
19%16%28%27%9%1
740
11th to 20thNight
26%15%26%24%7%1
760
21st to endNight
20%20%29%24%6%1
760
December1st to 10thNight
26%17%30%22%5%
760
11th to 20thNight
25%19%29%23%4
760
21st to endNight
28%17%30%22%3
836
Page generated at 2024-02-02 05:20:31. Version ac07

Copyright 2024 Attilla Danko


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